As digital multimedia has become more pervasive, and the tools by which to modify digital multimedia has become more available, it has become increasingly easy to copy, modify, and propagate digital content such images and video files. With a simple Internet connection and image processing tools, a user can obtain, alter and modify a digital image in a matter of minutes. Because of the quality of the available software, these alterations may be virtually undetectable to the human eye. Such ease of alteration becomes problematic, for example, in situations where digital images are used for secure or sensitive applications such as electronic commerce, licensed media distribution, documentation of insurance claims, and the transmission of images used for legal evidence.
Image authentication and detection is an issue for media content providers with regard to the copying and alteration of content. For example, a media content provider may need to determine whether a copyrighted image has been used without permission, or a news organization may want to monitor other content providers to determine if an image is used without payment and/or attribution, even if the image has been scaled or modified.
In another respect, a media content provider may want to detect whether a licensee has altered an image. For example, on a given day, a large news organization may send hundreds of images and video clips to licensed online, broadcast, and print news organizations all over the world. Even if a licensee modifies an image in a way that is readily detectable, for example, by adding a logo or watermark to the corner of the image, the task of verifying that all licensees are distributing unaltered images is difficult, especially when the disseminated images are scaled or reformatted.